Unlike many children, Jason Rosenfeld ’12 didn’t delude himself with dreams of athletic stardom. “As you could probably tell by looking at me,” he says in the opening minute of a Zoom interview, “I’m not tall or athletic enough to play sports professionally.”
But he was good at fantasy sports. After his school friends banned him from their leagues for winning too much, he covertly drafted a team for an un-banned friend, who then won. Fantasy sports can come down to luck, relying on your selected team staying injury-free and meeting expectations. “But if you know a lot more than your competitors,” Rosenfeld says, “there are a lot of inefficiencies you can exploit in the scoring system.” If he found that a fantasy league’s scoring system valued blocked shots at a disproportionate rate, he drafted the National Basketball Association’s best blockers—to the delayed dismay of his competition.
This kind of attention to statistical detail has worked well for Rosenfeld. By his thirtieth birthday, he had served as director of basketball analytics for the Charlotte Hornets, the Los Angeles Lakers, and the entire NBA. Now an analytics consultant and professor, he advises teams, athletes, and students across the world.
Rosenfeld grew up on Staten Island, the son of a teacher and guidance counselor, and the youngest of three siblings. Because everyone else there liked the New York Knicks, Rosenfeld, a contrarian, became a superfan of the Utah Jazz. He was especially devoted to their Hall of Fame point guard, John Stockton, who made up for his lack of height with supreme passing accuracy and unmatched basketball IQ. “He was like my basketball god,” Rosenfeld says.
He was accepted to Harvard in 2006, but took a gap year and worked at an investment-management firm in Manhattan. “And that’s what I thought I would do the rest of my life,” he recalls. “I liked working with numbers, and successful Harvard people work in finance.” But during that year he also read Moneyball, Michael Lewis’s book on Oakland Athletics general manager Billy Beane. Despite having a lower payroll to work with than most Major League Baseball general managers, his application of advanced statistics helped the team find undervalued talent and beat richer competition. Rosenfeld decided he could see himself doing something like that.
He began searching for Moneyball’s applications to basketball. The interest took him to the MIT campus for the first Sloan School of Management Sports Analytics Conference, in 2007. Rosenfeld walked up to the event’s relatively unknown co-organizer, Daryl Morey, then assistant general manager of the Houston Rockets, and asked if he could intern for free. A few weeks later, another staffer, Sam Hinkie—future general manager of the Philadelphia 76ers—asked if he was still interested. Rosenfeld said yes.
For the next five years, most of his weekends were spent interning (without pay) for the Rockets, who were aggressively tracking statistics to help draft, develop, and coach players. Under Morey, who took over as general manager right before Rosenfeld’s freshman year in 2007, the Rockets began launching a much greater percentage of three-point shots—determined to be more efficient than most two-point shots—and ignoring traditional positions. Watching college athletes from his dorm, Rosenfeld tracked not just their three-point attempts, but the precise distance of each one—helping Morey analyze how their shooting would translate to the NBA and its more distant three-point arc. (Statistics played a more personal role too; he met his wife, Evelyn Deng ’09, in Stat 111.)
He also learned Mandarin, a strategic choice. With the NBA becoming increasingly popular in China, boosted by the star power of Rockets center Yao Ming, Rosenfeld decided the language would give him a leg up on other aspiring analysts. It paid off unexpectedly well. As he began a second gap year in Beijing in 2009, he received news that Yao had purchased the Shanghai Sharks. Yao’s agent, who knew Rosenfeld through the Rockets, asked if he wanted to help run the struggling franchise. With no prior paid experience, Rosenfeld became an executive on a professional team.
He helped pick a coach and prepared him for each game, explaining opponents’ stylistic tendencies and translating stat sheets from Chinese to English. He also built analytics and video departments from scratch. Soon, the Sharks were collecting more sophisticated data than they had ever had: tracking where players took shots, how often they made them, where they were fouled, and a variety of factors that helped team members know their tendencies and take better shots.
The Sharks rose from among the league’s worst teams to one of its best. The local media, amused that a Harvard kid was running the analytics staff, enjoyed writing stories about this unconventional executive. “It was just a surreal experience,” Rosenfeld says. “I was reading, in a foreign language, things about me that weren’t true.” It was, he says, the most fun, most exciting year of his life.
He wanted the fun to continue. His senior year, he reached out to every team in the NBA, more than 100 college basketball programs, and organizations in Europe and in China. It was the Charlotte Hornets, owned by Michael Jordan, who offered him a job: to lead the basketball analytics research group and hire a staff. Their goal, simply put, was to help the team make better decisions and win more games: “Who should we draft? Who should we sign? Who should we trade for? And then on the coaching side, which players should play together? How should we prepare for opponents?”
After a couple of years, he left that job for the league office, where he helped answer questions like whether the NBA should decrease the number of games in a season or add a four-point line. He also led the push for “hustle stats” and hired people to track previously unrecorded statistics like shots contested, box-outs, and deflections—a way to recognize scrappy players who didn’t stand out by the conventional metrics. Rosenfeld says, half-seriously, that he was partial to hustle stats because they rewarded players like him. “It’s kind of a joke talking about me as a player because I’m so irrelevant at any level of basketball,” he explains. “But there are things I’ve done or would do, if I have the opportunity to play five on five anytime soon…that would help the team win.” Rosenfeld can’t dunk, but he can set a nice ball screen. The NBA now recognizes such contributions.
During Rosenfeld’s 15 years of experience, basketball analytics has advanced immeasurably. Stats recorded manually by Rosenfeld during his freshman year are now tracked by cameras installed on stadium ceilings. Positions that used to require Microsoft Excel aptitude now require a statistics Ph.D. Yet Rosenfeld has learned over the years that the data don’t speak for themselves. If he’s trying to help a team play better, emailing a 50-page PDF to a coach won’t do. As he’s told his students at New York University and Columbia, where he’s served as an adjunct professor, one page with a few key points and a visualization is better. And while Rosenfeld believes statistics can be useful in making decisions, talent is more important. “The Lakers were bad when I was there,” he says. “They got LeBron…then they added Anthony Davis. They got a lot better.”
For Rosenfeld, there’s nothing cooler than watching a game and seeing something he worked on affect on-court play—whether it’s a certain player shooting more from the right corner or a certain defense being deployed to stifle a powerful center. Though his friends have un-banned him from their leagues, he’s happy to sit them out. Consulting for teams and helping students and former players find their way into basketball roles, he finds his NBA dreams are no longer just a fantasy.
